EP0163428B1 - Rotary head type magnetic recording and/or reproducing apparatus - Google Patents
Rotary head type magnetic recording and/or reproducing apparatus Download PDFInfo
- Publication number
- EP0163428B1 EP0163428B1 EP85303028A EP85303028A EP0163428B1 EP 0163428 B1 EP0163428 B1 EP 0163428B1 EP 85303028 A EP85303028 A EP 85303028A EP 85303028 A EP85303028 A EP 85303028A EP 0163428 B1 EP0163428 B1 EP 0163428B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- frequency
- signal
- recording
- fmi
- fmr
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 230000005236 sound signal Effects 0.000 claims description 95
- 238000001514 detection method Methods 0.000 claims description 70
- 238000006243 chemical reaction Methods 0.000 claims 2
- 238000000926 separation method Methods 0.000 claims 2
- 238000000034 method Methods 0.000 description 8
- 238000010586 diagram Methods 0.000 description 5
- 239000003990 capacitor Substances 0.000 description 4
- 239000010410 layer Substances 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- 238000009499 grossing Methods 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 230000009467 reduction Effects 0.000 description 3
- 238000001228 spectrum Methods 0.000 description 3
- 230000005540 biological transmission Effects 0.000 description 2
- 230000008030 elimination Effects 0.000 description 2
- 238000003379 elimination reaction Methods 0.000 description 2
- 230000032258 transport Effects 0.000 description 2
- 230000003321 amplification Effects 0.000 description 1
- 239000000969 carrier Substances 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 125000004122 cyclic group Chemical group 0.000 description 1
- 230000005347 demagnetization Effects 0.000 description 1
- 230000001788 irregular Effects 0.000 description 1
- 238000003199 nucleic acid amplification method Methods 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 239000002344 surface layer Substances 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/02—Recording, reproducing, or erasing methods; Read, write or erase circuits therefor
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N9/00—Details of colour television systems
- H04N9/79—Processing of colour television signals in connection with recording
- H04N9/80—Transformation of the television signal for recording, e.g. modulation, frequency changing; Inverse transformation for playback
- H04N9/82—Transformation of the television signal for recording, e.g. modulation, frequency changing; Inverse transformation for playback the individual colour picture signal components being recorded simultaneously only
- H04N9/83—Transformation of the television signal for recording, e.g. modulation, frequency changing; Inverse transformation for playback the individual colour picture signal components being recorded simultaneously only the recorded chrominance signal occupying a frequency band under the frequency band of the recorded brightness signal
- H04N9/835—Transformation of the television signal for recording, e.g. modulation, frequency changing; Inverse transformation for playback the individual colour picture signal components being recorded simultaneously only the recorded chrominance signal occupying a frequency band under the frequency band of the recorded brightness signal involving processing of the sound signal
- H04N9/8355—Transformation of the television signal for recording, e.g. modulation, frequency changing; Inverse transformation for playback the individual colour picture signal components being recorded simultaneously only the recorded chrominance signal occupying a frequency band under the frequency band of the recorded brightness signal involving processing of the sound signal the sound carriers being frequency multiplexed between the luminance carrier and the chrominance carrier
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
- G11B20/02—Analogue recording or reproducing
- G11B20/06—Angle-modulation recording or reproducing
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
- G11B20/22—Signal processing not specific to the method of recording or reproducing; Circuits therefor for reducing distortions
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/02—Recording, reproducing, or erasing methods; Read, write or erase circuits therefor
- G11B5/027—Analogue recording
- G11B5/035—Equalising
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N5/00—Details of television systems
- H04N5/76—Television signal recording
- H04N5/91—Television signal processing therefor
- H04N5/93—Regeneration of the television signal or of selected parts thereof
- H04N5/95—Time-base error compensation
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N9/00—Details of colour television systems
- H04N9/79—Processing of colour television signals in connection with recording
- H04N9/80—Transformation of the television signal for recording, e.g. modulation, frequency changing; Inverse transformation for playback
- H04N9/802—Transformation of the television signal for recording, e.g. modulation, frequency changing; Inverse transformation for playback involving processing of the sound signal
Definitions
- the present invention generally relates to rotary head type magnetic recording and/or reproducing apparatuses, and more particularly to a rotary head type magnetic recording and/or reproducing apparatus designed to carry out recording and/or reproduction without being affected by the eccentricity in the rotation of a rotary magnetic head or heads when recording and/or reproducing an audio signal on and/or from a magnetic recording medium by use of the rotary magnetic head or heads.
- a magnetic recording and reproducing apparatus which records and reproduces a television video signal which occupies a wide frequency band
- rotary magnetic heads are conventionally used as the magnetic heads.
- the relative speed between the magnetic tape and the magnetic head is set to a predetermined large speed so as to enable the recording of an angular modulated signal which is obtained by subjecting the television video signal to an angular modulation.
- the recording and reproduction can be carried out for a long peroid of time without requiring an excessively large quantity of magnetic tape.
- Such a magnetic recording and reproducing apparatus is widely reduced to practice, and a magnetic recording and reproducing apparatus (video tape recorder or simply called VTR) for home using one or more rotary magnetic heads is popular all over the world.
- VTR video tape recorder
- the moving speed of the magnetic tape is set to an extremely slow speed of a several centimers per second, and the recording and reproduction are carried out by the rotary magnetic head which performs a helical scan.
- the recording and reproduction are carried out by the rotary magnetic head which performs a helical scan.
- the recording and reproduction of the audio signal are generally carried out by a stationary magnetic head which records and reproduces the audio signal on and from an audio track which extends in the longitudinal direction of the magnetic tape along one edge of the magnetic tape. For this reason, there is a problem in that it is impossible to obtain reproduced sound of a high quality.
- the above VTR can easily record and reproduce on and from the magnetic tape an audio signal having a wide frequency band. Hence, there are cases where the VTR is used solely for the recording and reproduction of the audio signal.
- the two rotary magnetic heads mounted on the rotary drum are alternately used so as to successively scan over the tracks on the magnetic tape.
- the actual frequency deviation is 2Af.
- the rate Av becomes equal to 0.9998387.
- the frequency fo of the signal to be recorded is equal to 1.7 MHz
- the frequency deviation ⁇ f becomes equal to 274 Hz
- an unwanted signal (a fundamental wave having a frequency corresponding to the rotational speed of the rotary drum and harmonics thereof) having the level of 39.2 dB with respect to the reproduced signal level when the frequency modulated audio signal has the reference frequency deviation, is always mixed into the reproduced signal.
- the frequency drift described before scarcely introduces problems when the recorded signal is reproduced from the magnetic tape on the same magnetic recording and reproducing apparatus which actually recorded the signal on the magnetic tape. No problems are introduced in this case because the frequency drift at the time of the recording is mutually cancelled with the frequency drift at the time of the reproduction.
- a serious problem occurs since the frequency drift at the time of the reproduction is added to the frequency drift at the time of the recording and the frequency drift is substantially doubled.
- US ⁇ A ⁇ 4 136 364 discloses a magnetic recording or reproducing apparatus according to the preambles of Claims 1 and 4 comprising recording means for recording a recording signal on a magnetic by means of a fixed recording head and frequency modulating means for obtaining a frequency-modulated signal within a frequency range of 465 ⁇ 140 Hz or 225 ⁇ 80 Hz by frequency-modulating a carrier by a signal which is to be recorded.
- Detection signal generating means generate a frequency drift detection signal having a constant frequency of 1800 Hz.
- the apparatus thus provides a wow and flutter reduction system in which two input signals and a reference signal are recorded and reproduced by a three-channel recording and reproducing system. This system is applicable to magnetic tape transports of the fixed type in which the tape is transported at a speed which is as constant as possible past the magnetic head(s). The small cyclic and irregular speed variations which inevitably occur in the mechanical transport can thus be compensated at least partially.
- a rotary head type magnetic recording and/or reproducing apparatus which records by rotary magnetic heads a signal at least including an angular modulated audio signal.
- the apparatus records on a magnetic recording medium a detection signal having a constant frequency together with the angular modulated audio signal by use of the rotary magnetic heads.
- the recorded signal is reproduced from the magnetic recording medium by use of the rotary magnetic heads, and the detection signal within the reproduced signal is subjected to an angular demodulation so as to obtain a demodulated signal.
- a correction signal for correcting the frequency deviation is obtained based on the demodulated signal.
- the correction signal is subtracted from a signal which is obtained by subjecting to an angular demodulation the angular modulated audio signal within the reproduced signal.
- Figure 6 is a concrete circuit diagram showing a part of the block system shown in Figure 5.
- FIG. 1 Left and right channel audio signals SI and Sr applied to respective input terminals 10 and 11, are subjected to a predetermined signal processing in respective audio signal processing circuits 12 and 13.
- Each of the audio signal processing circuits 12 and 13 is constituted by a noise reduction circuit, a pre-emphasis circuit and the like.
- An output signal of the audio signal processing circuit 12 is supplied to a frequency modulator 14wherein the signal frequency-modulates a carrier having a frequency f1.
- An output frequency modulated audio signal FM1 of the frequency modulator 14 is supplied to an adding circuit 16.
- an output signal of the audio signal processing circuit 13 is supplied to a frequency modulator 15 wherein the signal frequency-modulates a carrier having a frequency f2.
- An output frequency modulated audio signal FMr of the frequency modulator 15 is also supplied to the adding circuit 16.
- the frequencies f1 and f2 of the carriers and the frequency bands of the frequency modulated audio signals FMI and FMr are selected so as not to overlap with each other, as may be seen in the frequency spectrums shown in Figure 2.
- an NTSC system color video signal Sv having such a signal format that a carrier chrominance signal is band-share- multiplexed to a luminance signal within the frequency band of the luminance signal, is applied to an input terminal 17.
- the color video signal Sv is supplied to a video signal processing circuit 18 wherein the carrier chrominance signal and the luminance signal are separated.
- the separated luminance signal frequency-modulates a carrier and is formed into a frequency modulated luminance signal FMy
- the separated carrier chrominance signal is frequency-converted into a low frequency band and is formed into a frequency converted carrier chrominance signal Cx.
- the frequency modulated luminance signal FMy and the frequency converted carrier chrominance signal Cx occupy frequency bands shown in Figure 2.
- the frequency modulated audio signals FMI and FMr exist between the frequency bands of the frequency modulated luminance signal FMy and the frequency converted carrier chrominance signal Cx.
- the output signals FMy and Cx of the video signal processing circuit 18 are supplied to the adding circuit 16 and are added and frequency-multiplexed with the frequency modulated audio signals FMI and FMr from the frequency modulators 14 and 15.
- a detection signal generating circuit 19 generates a frequency drift detection signal Sfd having a constant frequency f3 and supplies this detection signal Sfd to the adding circuit 16.
- the detection signal Sfd is frequency-multiplexed with each of the signals in the adding circuit 16.
- the frequency f3 of the detection signal Sfd is selected to a frequency existing between the frequencies of the signals FM1 and Fx.
- An output frequency multiplexed signal of the adding circuit 16, having the frequency spectrum shown in Figure 2 is passed through a switch 21 which is connected to a terminal R in the recording mode of the apparatus and a head switching circuit 22, and is supplied to rotary magnetic heads 23a and 23b.
- the rotary heads 23a and 23b are provided diametrically on a rotary drum 24 and rotate together with the rotary drum 24.
- a magnetic tape 25 is wrapped obliquely around the outer peripheral surface of the rotary drum 24 over an angular range which is slightly greater than 180°, and the rotary heads 23a and 23b alternately record the signal supplied thereto on oblique tracks on the moving magnetic tape 25.
- the switch 21 is connected to a terminal P.
- the signal recorded on the magnetic tape 25 is alternately reproduced by the rotary heads 23a and 23b.
- the reproduced signals which are alternately and successively obtained from the rotary heads 23a and 23b, are passed through the head switching circuit 22 which has the known circuit construction, and are formed into a continuous signal.
- the reproduced signal from the head switching circuit 22 is passed through the switch 21 and is supplied to a reproducing amplifier 26.
- An output signal of the reproducing amplifier 26 is supplied to bandpass filters 27, 28, and 33, a highpass filter 40, and a lowpass filter 41.
- the bandpass filter 27 obtains the frequency modulated audio signal FM1 having the center frequency f1 from the reproduced signal supplied thereto, and supplies the frequency modulated audio signal FM1 to a frequency demodulator 29 wherein the frequency modulated audio signal FM1 is frequency-demodulated. An output signal of the frequency demodulator 29 is supplied to a subtracting circuit 31.
- the bandpass filter 28 obtains the frequency modulated audio signal FMr having the center frequency f2 from the reproduced signal supplied thereto, and supplies the frequency modulated audio signal FMr to a frequency demodulator 30 wherein the frequency modulated audio signal FMr is frequency-demodulated. An output signal of the frequency demodulator 30 is supplied to a subtracting circuit 32.
- the bandpass filter 33 obtains the detection signal Sfd having the frequency f3 from the reproduced signal supplied thereto, and supplies the detection signal Sfd to a frequency demodulator 34 wherein the detection signal Sfd is frequency-demodulated.
- a frequency demodulator 34 wherein the detection signal Sfd is frequency-demodulated.
- the output signal of the frequency demodulator 34 is supplied to a frequency drift correction signal forming circuit 35 wherein the signal is subjected to a signal processing including elimination of the signal component having the frequency f3, matching of the timing, amplification, and level adjustment.
- An output signal of the correction signal forming circuit 35 is supplied to the subtracting circuits 31 and 32 as a frequency drift correction signal.
- the subtracting circuits 31 and 32 eliminate the frequency drift component included in the demodulated left and right channel audio signals from the respective frequency demodulators 29 and 30, by subtracting the output correction signal of the correction signal forming circuit 35 from the respective demodulated left and right channel audio signals.
- Output audio signals of the subtracting circuits 31 and 32 are supplied to respective audio signal processing circuits 36 and 37 and are each subjected to a predetermined signal processing.
- Each of the audio signal processing circuits 36 and 37 include a noise reduction circuit which comprises a decoder, a de-emphasis circuit and the like. Reproduced left and right channel audio signals SI and Sr having no frequency drift are obtained through respective output terminals 38 and 39.
- the highpass filter 40 obtains the frequency modulated luminance signal FMy from the reproduced signal supplied thereto, and the lowpass filter 41 obtains the frequency converted carrier chrominance signal Cx from the reproduced signal supplied thereto.
- the frequency modulated luminance signal FMy from the highpass filter 40 and the frequency converted carrier chrominance signal from the lowpass filter 41 are supplied to a video signal processing circuit 42.
- the video signal processing circuit 42 frequency-demodulates the frequency modulated luminance signal FMy into the original luminance signal, and frequency-converts the frequency converted. carrier chrominance signal Cx into the original carrier chrominance signal which is returned to the original frequency band. Further, the video signal processing circuits 42 mixes the luminance signal and the carrier chrominance signal so as to obtain the original color video signal Sv, and the color video signal is obtained through an output terminal 43.
- the frequency drift correction signal forming circuit 35 comprises resistors R5 and R6, a coil L, a capacitor C1, a buffer amplifier A3, and variable resistors VR1 and VR2 coupled as shown in Figure 3.
- the variable resistors VR1 and VR2 are coupled in parallel, and a slider of the variable resistor VR1 is coupled to the non-inverting input terminal of the operational amplifier A1 within the subtracting circuit 31.
- a slider of the variable resistor VR2 is coupled to the non-inverting input terminal of the operational amplifier A2 within the subtracting circuit 32.
- the resistors R5 and R6, the coil L, and the capacitor C1 constitute a circuit which has the function of a delay circuit for matching the timing and also the function of a filter circuit for eliminating the signal component having the frequency f3.
- the carrier frequencies of the frequency modulated left channel audio signal FM1 and the frequency modulated right channel audio signal FMr are different. Generally, the higher the carrier frequency is, the larger the modulated and demodulated voltages are. For this reason, the voltage of the frequency drift correction signal with respect to the right channel audio signal having the higher carrier frequency, that is, the correction signal supplied to the subtracting circuit 32, must be higher than the voltage of the frequency drift correction signal with respect to the left channel audio signal having the lower carrier frequency, that is, the correction signal supplied to the subtracting circuit 31. Accordingly, the correction signals supplied to the subtracting circuits 31 and 32 are adjusted by the variable resistors VR1 and VR2 so that the voltage of the correction signal supplied to the subtracting circuit 32 is higher than the voltage of the correction signal supplied to the subtracting circuit 31. As a result, the left and right channel audio signals in which the frequency drift component has been similarly corrected, are obtained through the output terminal 54 and 55 and are supplied to the respective audio signal processing circuits 36 and 37.
- the frequency of the detection signal Sfd is selected to the frequency f3 which is between the frequencies of the frequency converted carrier chrominance signal Cx and the frequency modulated audio signal FM1.
- the frequency of the detection signal Sfd is not limited to the frequency f3.
- the frequency of the detection signal Sfd may be selected to a frequency fa between the frequencies of the frequency modulated audio signal FM1 and the frequency modulated audio signal FMr, or to a frequency fb between the frequencies of the frequency modulated audio signal FMr and the frequency modulated luminance signal FMy.
- the frequency of the detection signal Sfd simply needs to exist between the frequency bands occupied by the signals Cx, FMI, FMr, and FMy.
- the detection signal Sfd(a) in this case can be described by the following equations (3) and (4).
- the magnetic recording and reproducing transmission system generally has a non-linear characteristic, and the problem of interference of frequencies occurs. For this reason, it is more desirable to select the frequency of the detection signal Sfd to the frequency f3 or fb rather than to the frequency fa.
- the frequency of the detection signal Sfd must be selected so that frequencies which are the sume and the difference of the detection signal Sfd and the frequency modulated audio signal FMr do not exist within the frequency modulated audio signal FMI, and frequencies which are the sum and the difference of the detection signal Sfd and the frequency modulated audio signal FMI do not exist within the frequency modulated audio signal FMr.
- the frequency of the detection signal Sfd is high (that is, when the frequency of the detection signal Sfd is selected to the frequency fb)
- it is necessary to amplify the recording level in advance by taking into account the demagnetization effect and the like. But when such a measure is taken, a cross modulation easily occurs due to the effects of the non-linear characteristic of the recording transmission system and the like.
- the frequency of the detection signal Sfd when the frequency of the detection signal Sfd is low (that is, when the frequency of the detection signal Sfd is selected to the frequency f3), the level of the frequency drift correction signal which is obtained by frequency-demodulating the detection signal Sfd becomes somewhat smaller. In this case, the signal-to- noise (S/N) ratio becomes somewhat deteriorated by the subtracting processes performed in the subtracting circuits 31 and 32.
- the carrier frequencies f1 and f2 of the frequency modulated audio signals FMI and FMr are selected to 1.3 MHz and 1.7 MHz, respectively, and the frequency f3 of the detection signal Sfd is selected to 1.05 MHz.
- the output frequency modulated audio signals FMI and FMr of the frequency modulators 14 and 15 and the output detection signal Sfd of the detection signal generating circuit 19 are supplied to the adding circuit 16 wherein the three signals are added and frequency-multiplexed.
- the output signal of the adding circuit 16 is passed through a recording amplifier 20A, a switch 21A, and a head switching circuit 22A, and is then supplied to audio rotary heads 23aA and 23bA.
- the audio rotary heads 23aA and 23bA record the output signal of the adding circuit 16 on tracks formed obliquely to the longitudinal direction of the magnetic tape 25, at a deep (inner) layer part in the thickness direction of the magnetic tape 25.
- the output signal of the video signal processing circuit 18 is passed through a recording amplifier 20B, a switch 21B, and a head switching circuit 22B, and is then supplied to video rotary heads 23aB and 23bB.
- the video rotary heads 23aB and 23bB record the output signal of the video signal processing circuit 18 on tracks formed obliquely to the longitudinal direction of the magnetic tape 25, at a surface (outer) layer part in the thickness direction of the magnetic tape 25.
- the method of recording the audio signal at the deep layer part of the magnetic tape by use of a pair of rotary heads and recording the video signal at the surface layer part of the magnetic tape by use of another pair of rotary heads, is known.
- the signal reproduced by the rotary heads 23aA and 23bA is passed through the head switching circuit 22A, the switch 21A, and a reproducing amplifier 26A, and is then supplied to the bandpass filters 27, 28, and 33.
- the signal reproduced by the rotary heads 23aB and 23bB is passed through the head switching circuit 22B, the switch 21B and a reproducing amplifier 26B, and is then supplied to the highpass filter 40 and the lowpass filter 41.
- the operations of the remaining circuit part of the block system shown in Figure 4 are the same as those of the block system shown in Figure 1, and description thereof will be omitted.
- the recording of the signal on the magnetic tape and the reproduction of the signal from the magnetic tape are carried out on the same magnetic recording and reproducing apparatus, for convenience' sake.
- the recording of the signal on the magnetic tape and the reproduction of the signal from the magnetic tape are carried out on different magnetic recording and reproducing apparatuses. Therefore, according to the apparatus of the present invention, it is possible to effectively correct and eliminate the undesirable effects of the frequency drift which is caused by the eccentricity of the rotary drum.
- the quality of the output signals of the frequency demodulators 29 and 30 may be deteriorated in the subtracting circuits 31 and 32.
- the present embodiment contains improvements on the points described above.
- Figure 5 shows only the essential part of the present embodiment, and the illustration and description on the remaining parts will be omitted since the remaining parts are the same as the corresponding parts of the first embodiment.
- the signal obtained from the reproducing amplifier 26 or 26A is applied to an input terminal 61 and is supplied to the bandpass filters 27, 28, and 33.
- the output signal of the bandpass filter 33 is supplied to the frequency demodulator 34 and a switching signal forming circuit 62.
- the frequency demodulator 34 is coupled to the frequency drift correction signal forming circuit 35 through a normally-open switch 63.
- the switching signal forming circuit 62 forms a switching signal from the detection signal Sfd obtained from the bandpass filter 33 when the detection signal Sfd exists.
- the switch 63 is closed responsive to the switching signal from the switching signal forming circuit 62.
- the switch 63 when playing the magnetic tape which is not recorded with the detection signal Sfd, the switch 63 is open, and no signal is obtained from the frequency drift correction signal forming circuit 35. Thus, the output signals of the frequency demodulators 29 and 30 will not be subjected to an unwanted and unnecessary subtraction in the subtracting circuits 31 and 32.
- the switching signal when playing the magnetic tape which is recorded with the detection signal Sfd, the switching signal is produced from the switching signal forming circuit 62 and the switch 63 is closed by this switching signal.
- the correction and elimination of the frequency drift component is effectively performed in the subtracting circuits 31 and 32, similarly as in the case of the first embodiment described before.
- the switching signal forming circuit 62 comprises a buffer amplifier A11, capacitors C11 and C12, resistors R11, R12, and R13, a diode D, and an operational amplifier A12 which are coupled as shown in Figure 6.
- the diode D, the resistors R11 and R12, and the capacitors C11 and C12 constitute a rectifying and smoothing circuit, and this rectifying and smoothing circuit is coupled to a non-inverting input terminal of the operational amplifier A12.
- a non-inverting input terminal of the operational amplifier A12 is grounded through the resistor R13.
- the operational amplifier A12 and the resistors R12 and R13 constitute a comparator.
Landscapes
- Engineering & Computer Science (AREA)
- Signal Processing (AREA)
- Multimedia (AREA)
- Television Signal Processing For Recording (AREA)
- Recording Or Reproducing By Magnetic Means (AREA)
Description
- The present invention generally relates to rotary head type magnetic recording and/or reproducing apparatuses, and more particularly to a rotary head type magnetic recording and/or reproducing apparatus designed to carry out recording and/or reproduction without being affected by the eccentricity in the rotation of a rotary magnetic head or heads when recording and/or reproducing an audio signal on and/or from a magnetic recording medium by use of the rotary magnetic head or heads.
- Conventionally, as a most popularly employed magnetic recording and reproducing system for magnetically recording and reproducing an audio signal, there is a system which carries out recording and reproducing of the audio signal on and from a moving magnetic tape by use of a stationary magnetic head. The recording and reproducing of the audio signal is carried out by use of the A.C. bias system, for example, and the audio signal is directly recorded on the magnetic tape as it is, without being subjected to a signal processing such as modulation. In the present specification, such a method of directly recording the signal on the recording medium without subjecting the signal to a signal processing such as modulation, will be referred to as a direct recording method.
- When recording the signal which is to be recorded and reproduced on the magnetic tape according to the direct recording method, it is known that problems occur due to causes such as a change in the state of contact between the magnetic tape and the magnetic head and irregularities in a magnetic layer of the magnetic tape. Such problems include fluctuations in the amplitude of the signal which is recorded and reproduced, and the difficult compensation (equalization) of the characteristic when recording and reproducing a signal having a wide frequency band.
- It is also known that the problems introduced when recording the audio signal on the magnetic tape according to the direct recording method, can be eliminated satisfactorily by subjecting the audio signal which is to be recorded and reproduced to an angular modulation and recording an angular modulated signal (for example, a frequency modulated signal) on the magnetic tape. However, when recording and reproducing the audio signal in the form of the angular modulated signal, the frequency band of the signal which is recorded becomes wide compared to that of the signal which is recorded according to the direct recording method. Thus, when recording the angular modulated signal on the magnetic tape, a large relative speed is required between the magnetic tape and the magnetic head, and there is a problem in that a large quantity (length) of magnetic tape will be used per unit time. For this reason, the method of subjecting the signal to be recorded to such a modulation, is conventionally not employed in the magnetic recording and reproducing apparatus which uses the stationary magnetic head.
- In a magnetic recording and reproducing apparatus which records and reproduces a television video signal which occupies a wide frequency band, rotary magnetic heads are conventionally used as the magnetic heads. In such a magnetic recording and reproducing apparatus, the relative speed between the magnetic tape and the magnetic head is set to a predetermined large speed so as to enable the recording of an angular modulated signal which is obtained by subjecting the television video signal to an angular modulation. According to such a magnetic recording and reproducing apparatus, the recording and reproduction can be carried out for a long peroid of time without requiring an excessively large quantity of magnetic tape. Such a magnetic recording and reproducing apparatus is widely reduced to practice, and a magnetic recording and reproducing apparatus (video tape recorder or simply called VTR) for home using one or more rotary magnetic heads is popular all over the world. According to the VTR for home use, the moving speed of the magnetic tape is set to an extremely slow speed of a several centimers per second, and the recording and reproduction are carried out by the rotary magnetic head which performs a helical scan. As a result, it is possible to carry out the recording for several hours, for example, by use of a small quantity of magnetic tape.
- However, in the VTR for home use, the recording and reproduction of the audio signal are generally carried out by a stationary magnetic head which records and reproduces the audio signal on and from an audio track which extends in the longitudinal direction of the magnetic tape along one edge of the magnetic tape. For this reason, there is a problem in that it is impossible to obtain reproduced sound of a high quality.
- In order to eliminate the problem introduced in the VTR for home use, a VTR in which an angular modulated signal obtained by subjecting the audio signal to an angular modulation is recorded and reproduced on and from the magnetic tape by a pair of rotary magnetic heads having an extremely large relative speed between the magnetic tape and the magnetic head, has been reduced to practice.
- The above VTR can easily record and reproduce on and from the magnetic tape an audio signal having a wide frequency band. Hence, there are cases where the VTR is used solely for the recording and reproduction of the audio signal.
- No problems will occur when the reproduction of the angular modulated signal from the magnetic tape is carried out on the same VTR which recorded the angular modulated signal on the magnetic tape. However, when the reproduction of the angular modulated signal from the magnetic tape is carried out on a VTR which is different from the VTR which actually recorded the angular modulated signal on the magnetic tape, noise having a period related to the rotation period of a rotary drum which is mounted with the rotary magnetic heads mixes into the reproduced signal. As a result, the quality of the reproduced sound is greatly deteriorated, and it is difficult to carry out the recording and reproduction of the audio signal with a high fidelity.
- The problems of the above VTR have been studied. In other words, in a case where a rotary locus of the tip end part of each rotary magnetic head is not a perfect circle, a frequency drift (or fluctuation) is introduced in the reproduced signal through the recording and reproducing operations. When it is assumed that the rotary drum mounted with the rotary magnetic heads rotates with an eccentricity value Δx, a rate Av of the drift in the relative speed between one magnetic head and the magnetic tape can be described in terms of a radius r of the rotary drum and the eccentricity value Ax of the rotary drum as may be seen from the following equation (1).
- The two rotary magnetic heads mounted on the rotary drum are alternately used so as to successively scan over the tracks on the magnetic tape. Thus, the actual frequency deviation is 2Af.
- When it is assumed that the radius r of the rotary drum is equal to 31 mm and the eccentricity value Ax is equal to 5 pm, for example, the rate Av becomes equal to 0.9998387. When it is assumed that the frequency fo of the signal to be recorded is equal to 1.7 MHz, the frequency deviation Δf becomes equal to 274 Hz, and the signal to be recorded is constantly subjected to the frequency deviation 2Af=548 Hzp-p. In a case where the reference frequency deviation of the frequency modulated audio signal is equal to ±50 kHz, the frequency deviation 2Af=548 Hzp-p has a level of -39.2 dB with respect to the level of the reference frequency deviation.
- In other words, when there is an eccentricity of 5 um in the rotation of the rotary drum in the example given before, an unwanted signal (a fundamental wave having a frequency corresponding to the rotational speed of the rotary drum and harmonics thereof) having the level of 39.2 dB with respect to the reproduced signal level when the frequency modulated audio signal has the reference frequency deviation, is always mixed into the reproduced signal.
- The frequency drift described before scarcely introduces problems when the recorded signal is reproduced from the magnetic tape on the same magnetic recording and reproducing apparatus which actually recorded the signal on the magnetic tape. No problems are introduced in this case because the frequency drift at the time of the recording is mutually cancelled with the frequency drift at the time of the reproduction. However, in a caes where the recorded signal is reproduced from the magnetic tape on a magnetic recording and reproducing apparatus which is different from the magnetic recording and reproducing apparatus which actually recorded the signal on the magnetic tape, a serious problem occurs since the frequency drift at the time of the reproduction is added to the frequency drift at the time of the recording and the frequency drift is substantially doubled.
- US―A―4 136 364 discloses a magnetic recording or reproducing apparatus according to the preambles of Claims 1 and 4 comprising recording means for recording a recording signal on a magnetic by means of a fixed recording head and frequency modulating means for obtaining a frequency-modulated signal within a frequency range of 465±140 Hz or 225±80 Hz by frequency-modulating a carrier by a signal which is to be recorded. Detection signal generating means generate a frequency drift detection signal having a constant frequency of 1800 Hz. The apparatus thus provides a wow and flutter reduction system in which two input signals and a reference signal are recorded and reproduced by a three-channel recording and reproducing system. This system is applicable to magnetic tape transports of the fixed type in which the tape is transported at a speed which is as constant as possible past the magnetic head(s). The small cyclic and irregular speed variations which inevitably occur in the mechanical transport can thus be compensated at least partially.
- According to a first aspect of the invention, there is provided a recording apparatus as defined in the appended Claim 1.
- According to a second aspect of the invention, there is provided a recording and reproducing apparatus as defined in the appended Claim 4.
- Preferred embodiments of the invention are defined in the other appended claims.
- It is thus possible to provide a rotary head type magnetic recording and/or reproducing apparatus which records by rotary magnetic heads a signal at least including an angular modulated audio signal. At the time of the recording, the apparatus records on a magnetic recording medium a detection signal having a constant frequency together with the angular modulated audio signal by use of the rotary magnetic heads. At the time of the reproduction, the recorded signal is reproduced from the magnetic recording medium by use of the rotary magnetic heads, and the detection signal within the reproduced signal is subjected to an angular demodulation so as to obtain a demodulated signal. A correction signal for correcting the frequency deviation is obtained based on the demodulated signal. The correction signal is subtracted from a signal which is obtained by subjecting to an angular demodulation the angular modulated audio signal within the reproduced signal.
- It is also possible to provide a rotary head type magnetic recording and/or reproducing apparatus which is designed so as not to obtain an unwanted false correction signal from a noise component when reproducing the angular modulated audio signal from a magnetic recording medium which is not recorded with the detection signal at the time of the recording.
- The present invention will be further described, by way of example, with reference to the accompanying drawings, in which:
- Figure 1 is a system block diagram showing a first embodiment of a rotary head type magnetic recording and reproducing apparatus according to the present invention;
- Figure 2 shows frequency spectrums of signals which are recorded and reproduced in the apparatus shown in Figure 1;
- Figure 3 is a concrete circuit diagram showing a part of the block system shown in Figure 1;
- Figure 4 is a system block diagram showing a modification of the first embodiment of the rotary head type magnetic recording and reproducing apparatus according to the present invention;
- Figure 5 is a system block diagram showing an essential part of a second embodiment of the rotary head type magnetic recording and reproducing apparatus according to the present invention; and
- Figure 6 is a concrete circuit diagram showing a part of the block system shown in Figure 5.
- First, a description will be given with respect to the block system of a first embodiment of the rotary head type magnetic recording and reproducing apparatus according to the present invention, by referring to Figure 1. Left and right channel audio signals SI and Sr applied to
respective input terminals signal processing circuits signal processing circuits signal processing circuit 12 is supplied to a frequency modulator 14wherein the signal frequency-modulates a carrier having a frequency f1. An output frequency modulated audio signal FM1 of thefrequency modulator 14 is supplied to an addingcircuit 16. Similarly, an output signal of the audiosignal processing circuit 13 is supplied to afrequency modulator 15 wherein the signal frequency-modulates a carrier having a frequency f2. An output frequency modulated audio signal FMr of thefrequency modulator 15 is also supplied to the addingcircuit 16. The frequencies f1 and f2 of the carriers and the frequency bands of the frequency modulated audio signals FMI and FMr are selected so as not to overlap with each other, as may be seen in the frequency spectrums shown in Figure 2. - For example, an NTSC system color video signal Sv having such a signal format that a carrier chrominance signal is band-share- multiplexed to a luminance signal within the frequency band of the luminance signal, is applied to an
input terminal 17. The color video signal Sv is supplied to a videosignal processing circuit 18 wherein the carrier chrominance signal and the luminance signal are separated. In the videosignal processing circuit 18, the separated luminance signal frequency-modulates a carrier and is formed into a frequency modulated luminance signal FMy, and the separated carrier chrominance signal is frequency-converted into a low frequency band and is formed into a frequency converted carrier chrominance signal Cx. The frequency modulated luminance signal FMy and the frequency converted carrier chrominance signal Cx occupy frequency bands shown in Figure 2. As shown in Figure 2, the frequency modulated audio signals FMI and FMr exist between the frequency bands of the frequency modulated luminance signal FMy and the frequency converted carrier chrominance signal Cx. The output signals FMy and Cx of the videosignal processing circuit 18 are supplied to the addingcircuit 16 and are added and frequency-multiplexed with the frequency modulated audio signals FMI and FMr from thefrequency modulators - On the other hand, a detection
signal generating circuit 19 generates a frequency drift detection signal Sfd having a constant frequency f3 and supplies this detection signal Sfd to the addingcircuit 16. The detection signal Sfd is frequency-multiplexed with each of the signals in the addingcircuit 16. For example, the frequency f3 of the detection signal Sfd is selected to a frequency existing between the frequencies of the signals FM1 and Fx. - An output frequency multiplexed signal of the adding
circuit 16, having the frequency spectrum shown in Figure 2, is passed through aswitch 21 which is connected to a terminal R in the recording mode of the apparatus and ahead switching circuit 22, and is supplied to rotarymagnetic heads rotary drum 24 and rotate together with therotary drum 24. Amagnetic tape 25 is wrapped obliquely around the outer peripheral surface of therotary drum 24 over an angular range which is slightly greater than 180°, and the rotary heads 23a and 23b alternately record the signal supplied thereto on oblique tracks on the movingmagnetic tape 25. - In the reproducing mode of the apparatus, the
switch 21 is connected to a terminal P. The signal recorded on themagnetic tape 25 is alternately reproduced by the rotary heads 23a and 23b. The reproduced signals which are alternately and successively obtained from the rotary heads 23a and 23b, are passed through thehead switching circuit 22 which has the known circuit construction, and are formed into a continuous signal. The reproduced signal from thehead switching circuit 22 is passed through theswitch 21 and is supplied to a reproducingamplifier 26. An output signal of the reproducingamplifier 26 is supplied tobandpass filters highpass filter 40, and alowpass filter 41. - The
bandpass filter 27 obtains the frequency modulated audio signal FM1 having the center frequency f1 from the reproduced signal supplied thereto, and supplies the frequency modulated audio signal FM1 to afrequency demodulator 29 wherein the frequency modulated audio signal FM1 is frequency-demodulated. An output signal of thefrequency demodulator 29 is supplied to a subtractingcircuit 31. On the other hand, thebandpass filter 28 obtains the frequency modulated audio signal FMr having the center frequency f2 from the reproduced signal supplied thereto, and supplies the frequency modulated audio signal FMr to afrequency demodulator 30 wherein the frequency modulated audio signal FMr is frequency-demodulated. An output signal of thefrequency demodulator 30 is supplied to a subtractingcircuit 32. - The
bandpass filter 33 obtains the detection signal Sfd having the frequency f3 from the reproduced signal supplied thereto, and supplies the detection signal Sfd to afrequency demodulator 34 wherein the detection signal Sfd is frequency-demodulated. In a case where the eccentricity exists in the rotational center of therotary drum 24 and the frqeuency drift which is caused by the eccentricity and is introduced in the signal which is recorded and reproduced is not cancelled by the recording and reproduction, an output signal of thefrequency demodulator 34 is in correspondence with the above frequency drift. - The output signal of the
frequency demodulator 34 is supplied to a frequency drift correctionsignal forming circuit 35 wherein the signal is subjected to a signal processing including elimination of the signal component having the frequency f3, matching of the timing, amplification, and level adjustment. An output signal of the correctionsignal forming circuit 35 is supplied to the subtractingcircuits circuits respective frequency demodulators signal forming circuit 35 from the respective demodulated left and right channel audio signals. - Output audio signals of the subtracting
circuits signal processing circuits signal processing circuits respective output terminals - The
highpass filter 40 obtains the frequency modulated luminance signal FMy from the reproduced signal supplied thereto, and thelowpass filter 41 obtains the frequency converted carrier chrominance signal Cx from the reproduced signal supplied thereto. The frequency modulated luminance signal FMy from thehighpass filter 40 and the frequency converted carrier chrominance signal from thelowpass filter 41 are supplied to a videosignal processing circuit 42. The videosignal processing circuit 42 frequency-demodulates the frequency modulated luminance signal FMy into the original luminance signal, and frequency-converts the frequency converted. carrier chrominance signal Cx into the original carrier chrominance signal which is returned to the original frequency band. Further, the videosignal processing circuits 42 mixes the luminance signal and the carrier chrominance signal so as to obtain the original color video signal Sv, and the color video signal is obtained through anoutput terminal 43. - Concrete circuit examples of the frequency drift correction
signal forming circuit 35 and the subtractingcircuits frequency demodulators respective terminals frequency demodulator 34 is applied to a terminal 53. An inverting input terminal of an operational amplifier A1 within the subtractingcircuit 31, is coupled to the terminal 51 through a resistor R1. A resistor R2 is coupled between an output terminal and a non-inverting input terminal of the operational amplifier A1. An inverting input terminal of an operational amplifier A2 within the subtractingcircuit 32, is coupled to the terminal 52 through a resistor R3. A resistor R4 is coupled between an output terminal and a non-inverting input terminal of the operational amplifier A2. - The frequency drift correction
signal forming circuit 35 comprises resistors R5 and R6, a coil L, a capacitor C1, a buffer amplifier A3, and variable resistors VR1 and VR2 coupled as shown in Figure 3. The variable resistors VR1 and VR2 are coupled in parallel, and a slider of the variable resistor VR1 is coupled to the non-inverting input terminal of the operational amplifier A1 within the subtractingcircuit 31. A slider of the variable resistor VR2 is coupled to the non-inverting input terminal of the operational amplifier A2 within the subtractingcircuit 32. The resistors R5 and R6, the coil L, and the capacitor C1 constitute a circuit which has the function of a delay circuit for matching the timing and also the function of a filter circuit for eliminating the signal component having the frequency f3. - The carrier frequencies of the frequency modulated left channel audio signal FM1 and the frequency modulated right channel audio signal FMr are different. Generally, the higher the carrier frequency is, the larger the modulated and demodulated voltages are. For this reason, the voltage of the frequency drift correction signal with respect to the right channel audio signal having the higher carrier frequency, that is, the correction signal supplied to the subtracting
circuit 32, must be higher than the voltage of the frequency drift correction signal with respect to the left channel audio signal having the lower carrier frequency, that is, the correction signal supplied to the subtractingcircuit 31. Accordingly, the correction signals supplied to the subtractingcircuits circuit 32 is higher than the voltage of the correction signal supplied to the subtractingcircuit 31. As a result, the left and right channel audio signals in which the frequency drift component has been similarly corrected, are obtained through theoutput terminal signal processing circuits - In the embodiment described heretofore, the frequency of the detection signal Sfd is selected to the frequency f3 which is between the frequencies of the frequency converted carrier chrominance signal Cx and the frequency modulated audio signal FM1. However, the frequency of the detection signal Sfd is not limited to the frequency f3. For example, the frequency of the detection signal Sfd may be selected to a frequency fa between the frequencies of the frequency modulated audio signal FM1 and the frequency modulated audio signal FMr, or to a frequency fb between the frequencies of the frequency modulated audio signal FMr and the frequency modulated luminance signal FMy. In other words, the frequency of the detection signal Sfd simply needs to exist between the frequency bands occupied by the signals Cx, FMI, FMr, and FMy.
- In a case where the frequency of the detection signal Sfd is selected to the frequency fa, the detection signal Sfd(a) in this case can be described by the following equations (3) and (4).
circuits - Next, a description will be given with respect to a modification of the first embodiment of the rotary head type magnetic recording and reproducing apparatus according to the present invention, by referring to Figure 4. In Figure 4, those parts which are the same as those corresponding parts in Figure 1 will be designated by the same reference numerals, and their description will be omitted.
- The output frequency modulated audio signals FMI and FMr of the
frequency modulators signal generating circuit 19 are supplied to the addingcircuit 16 wherein the three signals are added and frequency-multiplexed. The output signal of the addingcircuit 16 is passed through arecording amplifier 20A, aswitch 21A, and ahead switching circuit 22A, and is then supplied to audio rotary heads 23aA and 23bA. The audio rotary heads 23aA and 23bA record the output signal of the addingcircuit 16 on tracks formed obliquely to the longitudinal direction of themagnetic tape 25, at a deep (inner) layer part in the thickness direction of themagnetic tape 25. - On the other hand, the output signal of the video
signal processing circuit 18 is passed through arecording amplifier 20B, aswitch 21B, and ahead switching circuit 22B, and is then supplied to video rotary heads 23aB and 23bB. The video rotary heads 23aB and 23bB record the output signal of the videosignal processing circuit 18 on tracks formed obliquely to the longitudinal direction of themagnetic tape 25, at a surface (outer) layer part in the thickness direction of themagnetic tape 25. The method of recording the audio signal at the deep layer part of the magnetic tape by use of a pair of rotary heads and recording the video signal at the surface layer part of the magnetic tape by use of another pair of rotary heads, is known. - In the reproducing mode, the signal reproduced by the rotary heads 23aA and 23bA is passed through the
head switching circuit 22A, theswitch 21A, and a reproducingamplifier 26A, and is then supplied to the bandpass filters 27, 28, and 33. The signal reproduced by the rotary heads 23aB and 23bB is passed through thehead switching circuit 22B, theswitch 21B and a reproducingamplifier 26B, and is then supplied to thehighpass filter 40 and thelowpass filter 41. The operations of the remaining circuit part of the block system shown in Figure 4 are the same as those of the block system shown in Figure 1, and description thereof will be omitted. - In the embodiment and the modification described heretofore, the recording of the signal on the magnetic tape and the reproduction of the signal from the magnetic tape are carried out on the same magnetic recording and reproducing apparatus, for convenience' sake. However, there are generally more cases where the recording of the signal on the magnetic tape and the reproduction of the signal from the magnetic tape are carried out on different magnetic recording and reproducing apparatuses. Therefore, according to the apparatus of the present invention, it is possible to effectively correct and eliminate the undesirable effects of the frequency drift which is caused by the eccentricity of the rotary drum.
- Next, a description will be given with respect to a second embodiment of the rotary head type recording and reproducing apparatus according to the present invention, by referring to Figure 5. In a case where the magnetic tape which is recorded with the detection signal Sfd as in the case of the embodiment described before is played on the magnetic recording and reproducing apparatus according to the present invention, it is possible to effectively correct and eliminate the frequency drift component as described before. However, a magnetic tape which is recorded on a conventional magnetic recording and reproducing apparatus (that is, a magnetic recording and reproducing apparatus which is not provided with the detection
signal generating circuit 19 in the embodiment described before) which has been in existence before the apparatus of the present invention was proposed, is naturally not recorded with the detection signal Sfd described heretofore. - When the magnetic tape which is recorded on such a conventional magnetic recording and reproducing apparatus is played on the magnetic recording and reproducing apparatus according to the present invention, no detection signal Sfd existes at the output of the
bandpass filter 33 and a large noise component may be produced. In this case, a demodulated signal of the large noise component may be obtained from thefrequency demodulator 34, and an unwanted and false correction signal may be obtained from the frequency drift correctionsignal forming circuit 35. - As a result, the quality of the output signals of the
frequency demodulators circuits - The present embodiment contains improvements on the points described above. Figure 5 shows only the essential part of the present embodiment, and the illustration and description on the remaining parts will be omitted since the remaining parts are the same as the corresponding parts of the first embodiment. The signal obtained from the reproducing
amplifier input terminal 61 and is supplied to the bandpass filters 27, 28, and 33. The output signal of thebandpass filter 33 is supplied to thefrequency demodulator 34 and a switchingsignal forming circuit 62. Thefrequency demodulator 34 is coupled to the frequency drift correctionsignal forming circuit 35 through a normally-open switch 63. The switchingsignal forming circuit 62 forms a switching signal from the detection signal Sfd obtained from thebandpass filter 33 when the detection signal Sfd exists. Theswitch 63 is closed responsive to the switching signal from the switchingsignal forming circuit 62. - Accordingly, when playing the magnetic tape which is not recorded with the detection signal Sfd, the
switch 63 is open, and no signal is obtained from the frequency drift correctionsignal forming circuit 35. Thus, the output signals of thefrequency demodulators circuits signal forming circuit 62 and theswitch 63 is closed by this switching signal. As a result, the correction and elimination of the frequency drift component is effectively performed in the subtractingcircuits - A concrete circuit example of the switching
signal forming circuit 62 is shown in Figure 6. In Figure 6, those parts which are the same as those corresponding parts in Figure 5 are designated by the same reference numerals. The switchingsignal forming circuit 62 comprises a buffer amplifier A11, capacitors C11 and C12, resistors R11, R12, and R13, a diode D, and an operational amplifier A12 which are coupled as shown in Figure 6. The diode D, the resistors R11 and R12, and the capacitors C11 and C12 constitute a rectifying and smoothing circuit, and this rectifying and smoothing circuit is coupled to a non-inverting input terminal of the operational amplifier A12. A non-inverting input terminal of the operational amplifier A12 is grounded through the resistor R13. The operational amplifier A12 and the resistors R12 and R13 constitute a comparator. - When the detection signal Sfd having the frequency f3 exists within the signal supplied to the buffer amplifier At from the
bandpass filter 33, a rectified voltage is introduced between the two terminals of the resistor R12 within the rectifying and smoothing circuit. The switching signal is introduced at the output of the operational amplifier A12 which constitutes the comparator, responsive to the rectified voltage. The output switching signal of the operational amplifier A12 is supplied to theswitch 63 so as to close theswitch 63.
Claims (12)
Applications Claiming Priority (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP87320/84 | 1984-04-28 | ||
JP59087320A JPS60231974A (en) | 1984-04-28 | 1984-04-28 | Sound signal processing system of rotary head type magnetic recording and reproducing device |
JP96267/84 | 1984-05-14 | ||
JP59096267A JPS60239966A (en) | 1984-05-14 | 1984-05-14 | Sound signal processing system in magnetic recording and reproducing device of rotary head type |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0163428A1 EP0163428A1 (en) | 1985-12-04 |
EP0163428B1 true EP0163428B1 (en) | 1990-07-18 |
Family
ID=26428610
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP85303028A Expired - Lifetime EP0163428B1 (en) | 1984-04-28 | 1985-04-29 | Rotary head type magnetic recording and/or reproducing apparatus |
Country Status (4)
Country | Link |
---|---|
US (1) | US4698693A (en) |
EP (1) | EP0163428B1 (en) |
KR (1) | KR900002352B1 (en) |
DE (2) | DE163428T1 (en) |
Families Citing this family (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH01107373A (en) * | 1987-10-21 | 1989-04-25 | Sony Corp | Data reproducing device |
US5337193A (en) * | 1988-09-24 | 1994-08-09 | Sony Corporation | Apparatus for selectively recording and/or reproducing a video signal with a PCM audio signal or with an FM audio signal |
DE69127322T2 (en) * | 1990-06-01 | 1997-12-18 | Victor Company Of Japan | Noise reduction and elimination apparatus for use with a rotating head recording and reproducing apparatus |
KR100300980B1 (en) * | 1998-03-14 | 2001-09-06 | 윤종용 | Hi-fi audio recording/playing apparatus using video head |
CN113490187A (en) * | 2020-03-16 | 2021-10-08 | 维沃移动通信有限公司 | Audio transmission method and electronic equipment |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4136364A (en) * | 1977-07-01 | 1979-01-23 | Signature Systems, Inc. | Multi-state wow and flutter reduction system and method |
DE2813207A1 (en) * | 1978-03-25 | 1979-10-04 | Bosch Gmbh Robert | SYSTEM FOR CORRECTION OF SIGNALS THAT ARE TAKEN FREQUENCY MODULATED FROM A RECORDING MEDIA |
JPS57140085A (en) * | 1981-02-23 | 1982-08-30 | Hitachi Ltd | Audio signal recording and reproducing circuit |
US4385327A (en) * | 1981-04-06 | 1983-05-24 | Pate John M | Audio system having a time base error correction arrangement |
DE3127818A1 (en) * | 1981-07-14 | 1983-02-03 | Siemens AG, 1000 Berlin und 8000 München | Process and apparatus for recording and reproducing signals on and from magnetic tapes |
-
1985
- 1985-04-25 KR KR1019850002821A patent/KR900002352B1/en not_active IP Right Cessation
- 1985-04-26 US US06/727,757 patent/US4698693A/en not_active Expired - Lifetime
- 1985-04-29 DE DE198585303028T patent/DE163428T1/en active Pending
- 1985-04-29 DE DE8585303028T patent/DE3578693D1/en not_active Expired - Fee Related
- 1985-04-29 EP EP85303028A patent/EP0163428B1/en not_active Expired - Lifetime
Also Published As
Publication number | Publication date |
---|---|
US4698693A (en) | 1987-10-06 |
DE3578693D1 (en) | 1990-08-23 |
KR850007502A (en) | 1985-12-04 |
EP0163428A1 (en) | 1985-12-04 |
DE163428T1 (en) | 1986-03-20 |
KR900002352B1 (en) | 1990-04-12 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US4647983A (en) | Method and apparatus for recording and/or reproducing color video signal | |
CA1182904A (en) | Videorecorder for recording a vision carrier that is frequency modulated with a video signal | |
US4651230A (en) | Apparatus for detecting and compensating drop-outs in an audio and video signal | |
US4490753A (en) | Audio signal recording and reproducing circuit | |
KR920003521B1 (en) | Magnetic recording/reproducing device | |
EP0163428B1 (en) | Rotary head type magnetic recording and/or reproducing apparatus | |
US4815061A (en) | Reproducing device for frequency modulated signals | |
US4492986A (en) | VTR With high-quality audio recording system | |
US4417284A (en) | Gain control circuit for a video tape recorder wherein the chrominance is gain controlled in response to the luminance signal as well as the chrominance signal | |
US4539602A (en) | Time axis correction device for multiplex information-carrying signal obtained from recording medium | |
JPH084349B2 (en) | Color video signal recording method and reproducing method thereof | |
JPS6123715B2 (en) | ||
US4672426A (en) | Chrominance signal processing apparatus | |
JPS6146682A (en) | Magnetic recording and recording device | |
US4335394A (en) | Crosstalk filtering arrangement with variable frequency filtering to remove effects of FM carrier | |
US4477837A (en) | Video signal recording-reproducing apparatus | |
US4541018A (en) | Dropout compensation and chrominance subcarrier frequency conversion circuit in a video signal reproducing apparatus | |
EP0170032A1 (en) | Magnetic recording-reproducing apparatus | |
JPS5870406A (en) | Device for correcting jitter of rotary head type magnetic recording and reproducing device | |
JP2559564B2 (en) | Video tape recorder | |
JPH028518B2 (en) | ||
JPH0828885B2 (en) | Secondary beat cancel circuit | |
JPH0243266B2 (en) | ||
JPS59200594A (en) | Chroma signal processing circuit | |
JPH0436637B2 (en) |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
|
AK | Designated contracting states |
Designated state(s): DE FR GB NL |
|
EL | Fr: translation of claims filed | ||
TCNL | Nl: translation of patent claims filed | ||
DET | De: translation of patent claims | ||
17P | Request for examination filed |
Effective date: 19860602 |
|
17Q | First examination report despatched |
Effective date: 19871204 |
|
GRAA | (expected) grant |
Free format text: ORIGINAL CODE: 0009210 |
|
AK | Designated contracting states |
Kind code of ref document: B1 Designated state(s): DE FR GB NL |
|
ET | Fr: translation filed | ||
REF | Corresponds to: |
Ref document number: 3578693 Country of ref document: DE Date of ref document: 19900823 |
|
PLBE | No opposition filed within time limit |
Free format text: ORIGINAL CODE: 0009261 |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT |
|
26N | No opposition filed | ||
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: FR Payment date: 19950411 Year of fee payment: 11 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: GB Payment date: 19950418 Year of fee payment: 11 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: DE Payment date: 19950421 Year of fee payment: 11 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: NL Payment date: 19950430 Year of fee payment: 11 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: GB Effective date: 19960429 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: NL Effective date: 19961101 |
|
GBPC | Gb: european patent ceased through non-payment of renewal fee |
Effective date: 19960429 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: FR Effective date: 19961227 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: DE Effective date: 19970101 |
|
NLV4 | Nl: lapsed or anulled due to non-payment of the annual fee |
Effective date: 19961101 |
|
REG | Reference to a national code |
Ref country code: FR Ref legal event code: ST |